The present invention generally relates to elastomeric contacts, and in particular to contacting arrangements and mechanical assemblies for contacting a plurality of electronic modules.
In complex electronic systems comprising a plurality of electronic modules and PC-boards (and therefore may have a high count of electrical contacts), the mechanical and electronic assembling of those modules and PC-boards has become more and more important. This is, on one hand, due to more and more complex and integrated structures and constraints in assembling space, and on the other hand, due to heat and cooling problems involved within the electronic system. Furthermore, a modular assembling is desirable.
Mechanical and electronic contacts provided by elastomeric materials (elastomeric contacts) are often used for achieving detachable connections. EP-A-0 238 410 and EP-A-0 558 855 disclose arrangements which use such elastomeric contacts for providing a resilient contact.
FIG. 1 shows the principal structure of an elastomeric contact 10 as known in the art. Elastomeric contacts 10 are electrically conductive contact media fibers, and an elastic carrier 30 such as silicone rubber, whereby the conductive elements 20 are normally embedded into the elastic carrier 30.
By applying pressure on adjacent sides of the elastomeric contact 10, e.g. by pressing the elastomeric contact 10 between a first PC-board 40 and a second PC-board 50, the carrier material 30 deforms elastically and the conductive elements 20 get in touch with corresponding contact areas of the first and second PC-board 40 and 50, and thus establish an electrical (and mechanical) contact between the first and second PC-board 40 and 50. The conductive elements 20 within the elastic carrier 30 can be arranged e.g. in rows (as indicated in FIG. 1) or in any other desired order.
A variety of elastomeric contacts 10 based on solid insulating silicone rubber is provided as GB-type inter-connectors by Shin-Etsu Polymer Company Ltd, Japan. For connecting small-pitch PC-boards, insulating sponge rubber may be applied to the solid rubber for support, as provided as a GN-type inter-connectors by Shin-Etsu Polymer Company Ltd, Japan.
GB-A-2 269 061 and U.S. Pat. No. 4,201,435 disclose elastomeric contacts, each comprising a unit with conductive elements embedded into a resilient material. In WO-A-96 22621, the conductive elements are partly embedded into a strengthening material. This unit is further embedded into a flexible and resilient material. Other elastomeric contacts are disclosed in U.S. Pat. No. 5,500,280 and GB-A-2 054 284.
It has been found that only a limited amount of pressure can be applied onto those elastomeric contacts 10 as known in the art, when a contact as shown in FIG. 1 is to be established. This is due to the elastic properties of the elastic carrier 30, so that the elastomeric contact 10 tends to "flow" when pressure is applied, meaning that the elastomeric contact 10 changes its internal and external shape and lateral dimensions under the influence of pressure. Particularly when the elastomeric contact 10 comprises a plurality of rows of conductive elements 20, the position of the contact areas of the elastomeric contact 10 provided by the individual conductive elements 20 might vary. This can lead to a mismatch in position of the contact areas of the elastomeric contact 10 with respect to the respective contact areas to be contacted, e.g. of the first and second PC-board 40 and 50, and thus to contact defects such as higher resistance or that no contact is established. Furthermore, the elastomeric contact 10 generally does not allow a thermal contact between the modules to be contacted, due to the low thermal conductivity of the elastomeric contact 10. GB-A-2 276 502 discloses an anisotropic conductive elastic connector comprising vertical conductive elements which are embedded into 3 horizontal layers of insulative elastic sheets, whereby a layer formed of a compressible foam synthetic resin material is provided between two adjacent layers formed of a resilient non-foam synthetic resin material. GB-A-2 276 502 overcomes the above mentioned disadvantages and solves the problem of "flowing". However, disadvantageous in the arrangement of GB-A-2 276 502 is that this arrangement is difficult to manufacture, e.g., since the conductive elements have to be kept aligned during the manufacturing process until all layers have been sequentially applied.
It is therefore an object of the present invention to provide a compressible elastomeric contact which is easier to manufacture.
As pointed out above, elastomeric contacts are often applied in contacting arrangements for providing an electrical contact between electronic modules. GB-A-2 276 502 further discloses a contacting arrangement for providing an electrical contact between a wiring board and an IC package. The arrangement comprises the above described elastomeric contact and a connector frame for positioning the elastomeric contact.
It is a further object of the invention to provide another contacting arrangement for providing an electrical contact between electronic modules.